Gypsum fibrosum and its major component CaSO4 increase cutaneous aquaporin-3 expression levels

Ethnopharmacological relevance We have previously reported that Byakkokaninjinto improves cutaneous pruritus by increasing the expression level of aquaporin-3 (AQP3). In this study, we examined the effect of Gypsum fibrosum (main component: CaSO 4 ), which is the main component of Byakkokaninjinto, on the cutaneous AQP3 expression level. Materials and methods KKAy mice were given a diet containing 0.3% Gypsum fibrosum extract, or a diet containing 0.3% CaSO 4 for 4 weeks. The urine volume, plasma glucose levels, cutaneous AQP3 protein expression, and the Ca 2+ content were measured. Results The 24-h urine volumes and the plasma glucose levels in the Gypsum fibrosum extract group were not significantly different from those in the control group. In the Gypsum fibrosum extract group, the cutaneous AQP3 protein levels increased significantly, by approximately 3.2-fold, compared to the control group. The cutaneous Ca 2+ content in the control group was approximately 35 μg/g. In the Gypsum fibrosum extract group, the Ca 2+ content increased to approximately 51 μg/g, which was significant compared to the control group. In the CaSO 4 group, an increase in the AQP3 protein expression levels and Ca 2+ content were observed; the extent of these increases were similar to those in the Gypsum fibrosum extract group. Conclusions The results of this study suggest that Gypsum fibrosum plays an important role in the increased levels of cutaneous AQP3 expression enhanced by Byakkokaninjinto. The results also indicate that the increase in AQP3 caused by Gypsum fibrosum is attributable to an increase in the cutaneous Ca 2+ content from its main component, CaSO 4 .